Four projects are planned for the next funding period. These include: (1) A study by light and electron microscopy of the indoleamine-accumulating cells in the retinas of rabbit, goldfish and Cebus monkey. (2) An analysis by electron microscopy of the synaptic organization of the catecholamine-containing cells (adrenergic junctional cells) in the rabbit retina. (3) A study by conventional and freeze fracture electron microscopic methods of gap junctions in representative vertebrate retinas. (4) An investigation of horseradish peroxidase uptake into synaptic terminals in both inner and outer plexiform layers of goldfish, skate and mudpuppy.